After much back and forth, James E. Hansen and I had agreed on a date to meet. Hansen, the director of NASA’s Goddard Institute for Space Studies, is the scientist most closely associated with climate change activists like Bill McKibben, who has led the charge against the Keystone XL pipeline, and Michael Brune, the executive director of the Sierra Club. In Hansen’s view, the country needs to start moving away from fossil fuels now, before the damage becomes irreversible.

As regular readers know, I believe the Obama administration should approve the Keystone pipeline, which would transport oil mined and processed from the tar sands of Alberta, Canada, to refineries in the Gulf of Mexico. Like it or not, fossil fuels are going to remain the world’s dominant energy source for the foreseeable future, and we are far better off getting our oil from Canada than, say, Venezuela. And the climate change effects of tar sands oil are, all in all, pretty small. I had the strong sense that Hansen hoped that once we met, I would begin to see the error of my ways.

The date we set was on Thursday, Feb. 14. The only glitch, he said, is that on the 13th, he was participating in an anti-Keystone demonstration in front of the White House led by his friend McKibben. The plan was they’d all try to get arrested.

“It is conceivable that we will be spending the night of the 13th in the clink, in which case it is not clear when I will arrive on the 14th,” Hansen wrote in an email. (He added, “Yes, I know, the merits of this continuing activity may be dubious, but Bill is working his butt off so hard that I can’t refuse.”) I postponed the meeting.

Suddenly, it appears, the Keystone XL pipeline, which President Barack Obama temporarily blocked during his re-election campaign, is back in the news. Nebraska, which had previously opposed the pipeline, recently dropped its opposition after TransCanada, the company hoping to build it, rerouted portions of it to avoid sensitive lands and aquifers. Canada, still miffed by Obama’s rejection of the pipeline last year, is threatening to sell the oil to China if the United States says no again.

In fact, this should be a no-brainer for the president, for all the reasons I stated earlier, and one more: the strategy of activists like McKibben, Brune and Hansen, who have made the Keystone pipeline their line in the sand, is utterly boneheaded.

Brune and McKibben have been very clear about what they hope to accomplish. Oil companies have invested upward of $100 billion to extract the unconventional oil in the sands. A pipeline is the only way to export it. The Keystone pipeline is Canada’s Plan A. Plan B is a pipeline to British Columbia, which would get the oil to China.

If the president blocks Keystone, and the First Nation tribes continue their staunch opposition to the western pipeline, then Canada will have the second largest oil reserves in the world — and no place to sell it. The environmental assumption of the activists is that by choking off the supply of new oil sources like the tar sands, the U.S. — and maybe the world — will be forced to switch more quickly to green energy.

Can you see how backward this logic is? As Adam Brandt, an energy expert at Stanford University, pointed out to me recently, so long as the demand is there, energy producers are going to search for new supplies of fossil fuel — many of them using unconventional means like tar sands extraction.

“With growing global demand, the economic pressure to develop unconventional resources is enormous and not going away,” he said. “Can environmental groups expect to win a series of fights for decades to come, when the economic forces are aligned very strongly against them in each round?”

The answer is obvious: no. The emphasis should be on demand, not supply. If the U.S. stopped consuming so much of the world’s oil, the economic need for the tar sands would evaporate.

On Monday, I finally spoke to Hansen. His knowledge and sincerity are easy to admire, even if his tactics are not. He told me he would like to see oil companies pay a fee, which would rise annually, based on carbon emissions. He said that such a tax could reduce emissions by 30 percent within 10 years.

Well, maybe. But it would also likely make the expensive tar sands oil more viable. If you really want to eliminate expensive new fossil fuel sources, the best way is to lower the price of oil, which would render them uneconomical. But, of course, that wouldn’t exactly lower demand either.

In any case, McKibben, Hansen and others were arrested on Wednesday, as planned. They spent a few hours in jail and paid $100 fines. And that was it.